Analysis of Age-Structured Population Models with an Additional Structure

It is illustrated that age-structured population models with an additional structure nicely fit into the framework of Lipschitz perturbations of non-dense operators which satisfy the resolvent estimates. This makes it not only possible to show that unique solutions to the model equations exist in a well-defined sense, but also that they generate a dynamical system (or semiflow) which leaves closed convex subsets invariant that satisfy an appropriate subtangential condition.